Glanders is a severe disease that has already been used as a bioweapon. It is naturally an equine disease but can be administered by aerosol for efficient human infection. Even if quickly diagnosed as Burkholderia mallei and treated, antibiotics do not control infections well. No vaccine has been developed, yet is a rational component of any plan for defense. It is increasingly clear that both safe and efficacious vaccines of the future should be based on subunit designs. Therefore, we propose to identify new, subunit vaccine candidates against glanders. We have engaged in a genomic-scale search of all B. mallei coding sequences for protective antigens. Using an aerosol challenge with virulent pathogen, we have sifted 200,000 genomic fragments to a number of lower complexity pools that protect hamsters and mice against lethal disease. This was accomplished by expression library immunization. Our specific approach to developing one or more subunit vaccines will be to 1) reduce the expression library to its individual protective components, 2) to characterize the immune responses correlated with protection and 3) prepare these new B. mallei antigens, and their homologs from the very closely related B. pseudomalllei, in three vaccine delivery modes. These compositions will be intended for testing in the relevant horse and monkey hosts in phase II of this proposal. At the conclusion of this phase I project we will have generated protective subunits and formulated them into three modalities for B. mallei, and perhaps B. pseudomallei, vaccines. The immune responses correlated with protection will be defined, which should facilitate optimal development of this vaccine and those for related pathogens, such as some Brucella and Pseudomonas species.